dbi::sql::nano.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "DBI::SQL::Nano 3"
.TH DBI::SQL::Nano 3 "2007-07-16" "perl v5.10.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
DBI::SQL::Nano \- a very tiny SQL engine
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 7
\& BEGIN { $ENV{DBI_SQL_NANO}=1 } # forces use of Nano rather than SQL::Statement
\& use DBI::SQL::Nano;
\& use Data::Dumper;
\& my $stmt = DBI::SQL::Nano::Statement\->new(
\&     "SELECT bar,baz FROM foo WHERE qux = 1"
\& ) or die "Couldn\*(Aqt parse";
\& print Dumper $stmt;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
DBI::SQL::Nano is meant as a *very* minimal \s-1SQL\s0 engine for use in situations where SQL::Statement is not available.  In most situations you are better off installing SQL::Statement although DBI::SQL::Nano may be faster for some very simple tasks.
.PP
DBI::SQL::Nano, like SQL::Statement is primarily intended to provide a \s-1SQL\s0 engine for use with some pure perl DBDs including \s-1DBD::DBM\s0, \s-1DBD::CSV\s0, DBD::AnyData, and DBD::Excel.  It isn't of much use in and of itself.  You can dump out the structure of a parsed \s-1SQL\s0 statement, but that's about it.
.SH "USAGE"
.IX Header "USAGE"
.Sh "Setting the \s-1DBI_SQL_NANO\s0 flag"
.IX Subsection "Setting the DBI_SQL_NANO flag"
By default, when a \s-1DBD\s0 uses DBI::SQL::Nano, the module will look to see if SQL::Statement is installed.  If it is, SQL::Statement objects are used.  If SQL::Statement is not available, DBI::SQL::Nano objects are used.
.PP
In some cases, you may wish to use DBI::SQL::Nano objects even if SQL::Statement is available.  To force usage of DBI::SQL::Nano objects regardless of the availability of SQL::Statement, set the environment variable \s-1DBI_SQL_NANO\s0 to 1.
.PP
You can set the environment variable in your shell prior to running your script (with \s-1SET\s0 or \s-1EXPORT\s0 or whatever), or else you can set it in your script by putting this at the top of the script:
.PP
.Vb 1
\& BEGIN { $ENV{DBI_SQL_NANO} = 1 }
.Ve
.Sh "Supported \s-1SQL\s0 syntax"
.IX Subsection "Supported SQL syntax"
.Vb 2
\& Here\*(Aqs a pseudo\-BNF.  Square brackets [] indicate optional items;
\& Angle brackets <> indicate items defined elsewhere in the BNF.
\&
\&  statement ::=
\&      DROP TABLE [IF EXISTS] <table_name>
\&    | CREATE TABLE <table_name> <col_def_list>
\&    | INSERT INTO <table_name> [<insert_col_list>] VALUES <val_list>
\&    | DELETE FROM <table_name> [<where_clause>]
\&    | UPDATE <table_name> SET <set_clause> <where_clause>
\&    | SELECT <select_col_list> FROM <table_name> [<where_clause>]
\&                                                 [<order_clause>]
\&
\&  the optional IF EXISTS clause ::=
\&    * similar to MySQL \- prevents errors when trying to drop
\&      a table that doesn\*(Aqt exist
\&
\&  identifiers ::=
\&    * table and column names should be valid SQL identifiers
\&    * especially avoid using spaces and commas in identifiers
\&    * note: there is no error checking for invalid names, some
\&      will be accepted, others will cause parse failures
\&
\&  table_name ::=
\&    * only one table (no multiple table operations)
\&    * see identifier for valid table names
\&
\&  col_def_list ::=
\&    * a parens delimited, comma\-separated list of column names
\&    * see identifier for valid column names
\&    * column types and column constraints may be included but are ignored
\&      e.g. these are all the same:
\&        (id,phrase)
\&        (id INT, phrase VARCHAR(40))
\&        (id INT PRIMARY KEY, phrase VARCHAR(40) NOT NULL)
\&    * you are *strongly* advised to put in column types even though
\&      they are ignored ... it increases portability
\&
\&  insert_col_list ::=
\&    * a parens delimited, comma\-separated list of column names
\&    * as in standard SQL, this is optional
\&
\&  select_col_list ::=
\&    * a comma\-separated list of column names
\&    * or an asterisk denoting all columns
\&
\&  val_list ::=
\&    * a parens delimited, comma\-separated list of values which can be:
\&       * placeholders (an unquoted question mark)
\&       * numbers (unquoted numbers)
\&       * column names (unquoted strings)
\&       * nulls (unquoted word NULL)
\&       * strings (delimited with single quote marks);
\&       * note: leading and trailing percent mark (%) and underscore (_)
\&         can be used as wildcards in quoted strings for use with
\&         the LIKE and CLIKE operators
\&       * note: escaped single quote marks within strings are not
\&         supported, neither are embedded commas, use placeholders instead
\&
\&  set_clause ::=
\&    * a comma\-separated list of column = value pairs
\&    * see val_list for acceptable value formats
\&
\&  where_clause ::=
\&    * a single "column/value <op> column/value" predicate, optionally
\&      preceded by "NOT"
\&    * note: multiple predicates combined with ORs or ANDs are not supported
\&    * see val_list for acceptable value formats
\&    * op may be one of:
\&         < > >= <= = <> LIKE CLIKE IS
\&    * CLIKE is a case insensitive LIKE
\&
\&  order_clause ::= column_name [ASC|DESC]
\&    * a single column optional ORDER BY clause is supported
\&    * as in standard SQL, if neither ASC (ascending) nor
\&      DESC (descending) is specified, ASC becomes the default
.Ve
.SH "ACKNOWLEDGEMENTS"
.IX Header "ACKNOWLEDGEMENTS"
Tim Bunce provided the original idea for this module, helped me out of the tangled trap of namespace, and provided help and advice all along the way.  Although I wrote it from the ground up, it is based on Jochen Weidmann's orignal design of SQL::Statement, so much of the credit for the \s-1API\s0 goes to him.
.SH "AUTHOR AND COPYRIGHT"
.IX Header "AUTHOR AND COPYRIGHT"
This module is written and maintained by
.PP
Jeff Zucker < jzucker \s-1AT\s0 cpan.org >
.PP
Copyright (C) 2004 by Jeff Zucker, all rights reserved.
.PP
You may freely distribute and/or modify this module under the terms of either the \s-1GNU\s0 General Public License (\s-1GPL\s0) or the Artistic License, as specified in
the Perl \s-1README\s0 file.